What a lovely idea here! This is a must for me as I have a huge number of those really boring hanging files. The original files are so boring that everytime I go next to them, I feel like just leaving them open so that I don't have to see that bold all-the-same looking cover when I look at them. This craft idea is awesome and adds some fun to those folders.
You can alter the type of paper you use but for the ones in the picture above, the maker has used wall-paper scraps and she has used spray adhesive to stuck them on folders.
Check out this for the rest of the tutorial.
Have a fun weekend!